Apparatus for grinding



30, 1952 w. G. BALDENHOFER 2,623,333

APPARATUS FOR GRINDING Filed March 9, 1948 2 SHEET-S--SHEET 1 INVENTOR BALDENHOFER 88 14 54. I I

ATTORNEYS Dec. 30, 1952 w. e. BALDENHOFER APPARATUS FOR GRINDING 2 SHEETS-SHEET 2 Filed March 9, 1948 IN VENTOR W6. B/IL DENHDFER WrW HTTORNE YS Patented Dec. 30, 1952 APPARATUS FOR GRINDING William G. Baldenhofer, Springfield, Ohio, as-

signor to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio Application March 9, 1948, Serial No. 13,795

2 Claims. (Cl. 51-95) This invention relates to grinding machines, and particularly to grinders for circular contour workpieces.

More particularly still, this invention relates to grinding machines having associated therewith a crush dressing roll for maintaining the wheel to shape within predetermined limits.

Grinders for circular contour workpieces are employed in many circumstances wherein multiple workpieces are to be produced or finished by a grinding operation.

Customarily the wheel shape is maintained between predetermined limits by an adjustable diamond truing device. Due to the limitations encountered in shaping a wheel with a diamond truing device, it has been found nearly impossible to adapt cylindrical grinding techniques to the production of workpieces with intricate forms thereon and to maintain a production rate compatible with present day requirements.

The primary object of the present invention is to provide an arrangement in connection with a grinder for circular contour workpieces wherein the wheel may be shaped to any intricate form desired.

Another object is to provide a simple crush forming arrangement in connection with a grinding machine for circular contour workpieces wherein the Wheel can be rapidly trued and then immediately employed for grinding a workpiece whereby a high speed overall grinding cycle results. i

It is a still further object of this invention to provide, in connection with a grinder for circular contour workpieces and a crush dressing roll for the wheel thereof, means for maintaining the shape of the dressing roll between predetermined limits.

These and other objects and advantages will become more apparent upon reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a front view, partly in section, of a typical grinder showing the arrangement thereof according to this invention;

Figure 2 is a plan view of the grinding machine having a portion of the frame thereof broken away to show the manner in which the Wheel supporting means is slidably supported thereon;

Figure 3 is a transverse section indicated by the line 3-3 on Figure 2 and shows further details in connection with the construction of the machine;

Figure 4 is a somewhat enlarged view showing how the dressing roll for the grinding wheel is mounted on the end of the spindle of the headstock of the grinding machine;

Figure 5 is a view looking in at the rear of the machine frame as indicated by the arrow 5 on Figure 2 and showing a solenoid arrangement for advancing the wheel toward the work axis of the machine;

Figure 6 is a diagrammatic View showing one form of gear train which can be built into the headstock of the machine for providing for different rates of rotational speed of the headstock spindle; and

Figure 7 is a wiring diagram showing one manner of connecting the several electrical elements to the source of electric power.

Referring to the drawings, the grinding ma chine shown therein comprises a bed Ill having reciprocably mounted thereon a table it. This table may be supported on the bed by the usual V and flat guideway arrangement as indicated at M in Figure 3. Reciprocable movements of the table on the bed may be had by the hyldraulic motor means indicated at 16 and which is mounted within the bed and which has its movable part connected with the table l2.

Stop means may be positioned at each end of the bed, one of which is indicated at 18, for predetermining the end positions of the table I2 thereby to bring the grinding wheel of the machine into relative alignment with the table at two different positions therealong.

The table [2 has mounted at the right end thereof a tailstock arrangement 20 and at the left end thereof a headstock arrangement 22. The tailstock includes a center 24, whereas the headstock includes a center 25, and these centers define a work axis between which is supported a workpiece 28 having a shaft 30, or the workpiece may be mounted on any suitable mandrel means adapted to be supported by the centers.

The headstock 22 has associated therewith a drive motor as indicated at 32 and which is belted by a drive belt 34 to the input shaft 35 of the headstock.

Between the input shaft 35 and the spindle 33 of the headstock which carries the center .25, there are change gears which are best seen in Figure 6. These change gears comprise a pair of different size gears 40 on the shaft 36 adapted for selectively meshing with the different size.

gears 42 slidable on the jackshaft 44 and which has also, slidable thereon and integral with the said gears 42, the gear 46 which meshes with the gear 48 on the spindle 38..v

A lever 50 mounted on the headstock provides means for shifting'the gears int'o'one drive ratio or the otheror into a neutral position. It will be understood that the gearing arrangement isonly exemplary of a great many types of various speed transmissions which could be interposed between the motor 32 and the driven spindle 38.

As will best be seen in Figure 4 the nose end or the spindle 38 is tapered as at 52 and mounted thereon is a crush forming roll This roll is retained on the tapered nose of the spindle by means of the screws 56 and the said tapered nose and screws maintain the crushing roll in rigid coaxial alignment with the work axis defined by the headstock and tailstock centers. I

Any suitable means may be employed for transmitting rotative power from the spindle as to the shaft or mandrel 39, but there is illustrated in Figure 4 a dog arrangement 58 which clamps around the shaft or mandrel 39 and which has projectin fingers engaging the screw holes in the crush forming roll 54.

Mounted adjacent the bed l6, and preferably connected therewith, is a column 68 having a guideway 62 therein extending transversely to the direction of reciprocation of the table Suspended in the guideway '62 is a wheel head arrangement E4 and carried thereby on a shaft extending parallel with the direction of reciprocation of the bed i2 is a grinding wheel 66. The shaft supporting the grinding wheel carries a drive pulley 58 at its other end and over which passes the drive belt H3.

The slide 64 is adjustable in the guideway 52 by means of a nut 72 upstanding from the said slide and through which there passes a drive screw i l. The screw 74 carries a hand wheel it at the operators side of the column $13 and has a ratchet wheel T8 mounted on the said screw at the other side of the column. This slide can be adjusted by the ratchet wheel it by energization of a solenoid S indicated in Figure 5, and which is connected with the rod 89 and pawl 82.

It will be apparent that when the solenoid S is ole-energized the pawl is positioned away from the ratchet wheel 18 thereby permitting free rotation of the screw M by the hand wheel '56. Energization of the solenoid S will move the pawl e2 rightwardly as viewed in Figure 5 and actuates the ratchet WheellB.

For maintaining the crushing roll 5d within predetermined limits there is a shaving tool 83 which is supported on a slide -84 so that the cutting edge of the tool is presented to the said roll substantially radially. This provides for a true shaving action and removes material from the periphery of the roll while maintaining the pe riphery very smooth. A suitable screw arrangement at 86 and a knurled knob 83 provide for manual adjustment of the shaving tool 83 toward and away from the roll 54.

It has been found that the best manner of crush forming a wheel is to feed it against the crushing roller in spaced increments of feed which occur at intervals equal to about one and a third revolutions of the said wheel. For accomplishing a feed of this nature the arrangement shown in Figure '7 may be employed.

In Figure '7 the solenoid S is shown connected with the power lines LI and L2 and in series with a normally open switch 9b which can be operated by a cam 82 into closed position. Also connected with the power lines Li and L2 is a motor 94 for driving the cam and in series therewith is a selector switch 95 and an adjustable rheostat 93.

Upon closing the switch 96 the motor 54 will drive the cam 92 for intermittently closing the switch 90 thereby intermittently to energize the solenoid S and to produce increments of feed of the grinding wheel 66 toward the work axis of the machine, while adjustment of the rheostat 98 will predetermine the rate at which these increments of feed take place.

The rate of speed at which the work spindle is driven during a grinding cycle is substantially greater than the speed at which it is driven during a dressing cycle. The variable speed transmissions shown in Figure 6 may, in most cases, accommodate for the speed differential, but in other cases, wherein the motor 32 for the headstock spindle is a direct curent motor, the said motor may be connected in circuit with a speed controlling rheostat I00 as shown in Figure '7. This will provide for any desired speed of the work spindle during a dressing operation.

Operation In operation, a crush forming roll of the proper configuration is mounted on the nose of the headstock spindle.

Assuming that the grinding wheel mounted in the wheel head is a plain wheel, it is first broken down to the proper shape by bringing it into engagement with the crushing roll and rotating the said wheel and roll together at a low surface speed, say, about 250 feet per minute. During this forming cycle, the switch 96 is closed to energize the motor 94 and therethrough to produce spaced increments of feed of the wheel toward the roll.

After the wheel has been shaped it is preferable to restore the configuration of the roll 54 by urging the shaving tool 33 thereagainst while maintaining the said roll in operation at a fairly low speed.

Thereafter the workpiece to be ground is mounted between the headstock and tailstock spindles and the table I2 is moved leftwardly on the bed to bring it into alignment with the formed grinding wheel. The grinding wheel is now driven at grinding speed, about 6,000 feet per minute surface speed, the headstock is energized to rotate the Work at its proper speed, and the wheel is moved toward the work axis until it comes into engagement with the work and grinds it to the proper size.

After the grinding operation is completed the wheel is retracted from the work, the work spindle is stopped, and the workpiece is removed therefrom.

This process may thereafter be repeated for as many workpieces as there are to be produced and with the wheel being intermittently trued by the crushing roll.

It will be apparent that a high rate of production can be maintained by the arangement of this invention and that high quality workpieces result because the wheel can always be dressed to restore its true configuration at any time and with very little loss of productive time of the machine. Also, because of the shaving tool associated with the crushing roll, it is not necessary to shut the machine down to replace the roll since it can be maintained to an accurate configuration by means of the shaving tool.

The coaxial arrangement of the workpiece and crushing roll is of advantage in requiring a minimum amount of manipulation of the relatively movable machine parts in order to bring the wheel into grinding or dressing position. This saves a substantial amount of time over a working day and increases the productivity of the machine.

It will be understood that this invention is susceptible to modification in order to adapt it to difierent usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a grinder for circular contour workpieces, a frame, a table reciprocable on said frame, a grinding wheel rotatable on an axis parallel to the direction of reciprocation of said table, a slide supporting said wheel and carried on said frame and movable transversely with respect to said table, a headstock including a rotatable spindle and a tailstock mounted on said table defining a work axis parallel to the axis of said wheel for supporting a workpiece to be ground on said work axis, a crush dressing roll mounted on the nose of said spindle coaxial with said workpiece, a drive for said spindle for rotation of said crush roll and workpiece together and independently of said grinding wheel, means for driving said table in one direction to bring said workpiece into alignment with said wheel and in the other direction to bring said roll into alignment with said wheel, and slide driving means for moving said wheel into selective aligned engagement with said crush roll or workpiece, said slide driving means including means operable to produce spaced increments of feed of said wheel towards said axis.

2. In a grinder for circular contour workpieces, a frame, a table reciprocable on said frame, a grinding wheel rotatable on an axis parallel to the direction of reciprocation of said table, a slide supporting said wheel and carried on said frame and movable transversely with respect to said table, a headstock including a rotatable spindle and a tailstock mounted on said table defining a work axis parallel to the axis of said wheel for supporting a workpiece to be ground on said work axis, a crush dressing roll mounted on the nose of said spindle coaxial with said workpiece, a drive for said spindle for rotation of said crush roll and workpiece together and independently of said grinding wheel, means for driving said table in one direction to bring said workpiece into alignment with said wheel and in the other direction to bring said roll into alignment with said wheel, and slide driving means for moving said wheel into selective aligned engagement with said crush roll or workpiece, said slide driving means including means operable to produce spaced increments of feed of said wheel towards said axis at each 1 /3 revolutions of said wheel.

WILLIAM G. BALDENHOFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 613,934 Norton Nov. 8, 1898 1,395,391 Conners Nov. 1, 1921 1,834,179 Place Dec. 1, 1931 2,220,768 Indge Nov. 5, 1940 2,237,974 Wainwright Apr. 8, 1941 2,385,644 Polk Sept. 25, 1945 2,436,527 Polk et al Feb. 24, 1948 FOREIGN PATENTS Number Country Date 518,019 Great Britain Feb. 15, 1940 OTHER REFERENCES Publication: Grits and Grinds, published by the Norton Co., February 1945, vol. 36, No. 2, pages 5, 6, 7 and 8. 

